Field of the Invention
The present invention relates to a hydraulic system and a working machine including the hydraulic system.
Discussion of the Background
A hydraulic system configured to change traveling speeds of a working machine by using a hydraulic motor of a variable displacement type is previously known in a technical field of the working machine, such as a skid steer loader and a compact track loader (see Japanese Unexamined Patent Application Publication No. 2013-36276).
The hydraulic system disclosed in Japanese Unexamined Patent Application Publication No. 2013-36276 is a system configured to change traveling speeds of the working machine by using an axial motor of a variable displacement type (an HST motor), the axial motor employing a swash plate. The hydraulic system includes a speed change mechanism configured to change a speed of the HST motor. The speed change mechanism includes: a direction switch valve; a hydraulic pressure switch valve having a position, the position being switched by the direction switch valve; and a swash plate switch cylinder connected to the hydraulic pressure switch valve and to the HST motor. The speed change mechanism firstly changes the position of the hydraulic pressure switch valve by using the direction switch valve, thereby stretching and shortening the swash plate switch cylinder. The stretching and shortening of the swash plate switch cylinder changes an angle of the swash plate of the HST motor, and then the HST motor is switched to a first speed or to a second speed.
In addition, the hydraulic system includes a brake mechanism configured to brake the HST motor. The brake mechanism is a negative brake, and includes: a brake part configured to be activated by a pressured hydraulic fluid to brake the HST motor; and a brake release valve configured to release the braking caused by the brake part.